The present invention relates to a drilling system.
Drilling, particularly oil-well drilling, is performed by means of a string of drill rods bearing a drilling tool at its bottom end, and driven in rotation at its top part. The upper end of the drill string is supported by a hoist through the medium of a block mounted at the top of a drilling derrick.
In the latest drilling installations, the rotation of the drill string is performed by means of a hydraulic motor installed on a motor-driven drilling head disposed between the hoist and the upper end of the string of rods. The injection of mud into the drill string is also performed from this drilling head.
Also known are drilling installations in which the successive additions of rods to the upper part of the drill string already in place are performed with the aid of an arm capable of picking the individual rods from a stack in which they are disposed horizontally, and of bringing them to the vertical above the drill string where they are then screwed at their upper end to the drive head and at their lower end to the upper end of the drill string already in place.
All these operations as well as the control of the mud pumps and hoist are performed manually.
In particular, the motor of the hoist is used only for raising the string of rods. During the drilling this motor is disengaged from the hoist and the descent of the string of rods is controlled by means of a manually operated drum brake. When a rapid descent is necessary, an electromagnetic retarder is also used.
The operator of the drilling installation therefore has at his disposal, for the control of the hoist alone, four controls, viz., the clutch, the drum retarder, the electromagnetic retarder and the hoist motor control.
Other workers must furthermore check the operation of the mud pumps and especially perform the operations of adding drill rods.
The operation of a drilling installation therefore calls for complex operations which have to be performed by a numerous crew under generally difficult conditions.
The present invention aims to relieve this difficulty.